Heretofore, low modulus characteristics of silicone rubbers have been desirable in accommodating joint movement due to vibration and thermal cycling since less stress is exerted on a sealant-metal bond interface. Such low modulus properties generally decrease the probability of oil leaks. However, oil resistance has been traditionally improved by utilizing comparatively high crosslink densities. The result was lower elongation properties and, hence, reduced movement capabilities. When fewer crosslinks were incorporated into the elastomer to lower the modulus, generally more rapid deterioration of the polymer backbone by nucleophilic or electrophilic agents occurred at elevated temperatures. Accordingly, room temperature vulcanizable elastomers having good oil resistance were generally not made.
U.S. Pat. No. 3,189,576 to Sweet relates to oxime curatives and to new organosilicon intermediates.
U.S. Pat. No. 4,323,489 as well as U.S. Pat. No. 3,962,160, both to Beers, generally relate to oxime curable room temperature vulcanizates. More specifically, the '489 patent relates to a vulcanizable silicone rubber composition with very low modulus containing a silanol end-stopped diorganopolysiloxane, a difunctional acetamide coupler as a chain extender and a minor amount of a compound containing an oxime functionality thereon as a trifunctional crosslinker.
U.S. Pat. No. 4,356,116 to Beers relates to a low volatile room temperature vulcanizable silicone rubber composition containing various components including a silanol polymer, a crosslinking agent, and a filler.
U.S. Pat. No. 3,517,001 to Berger relates to adhesion promoter compositions.
U.S. Pat. No. 4,100,129 to Beers also relates to adhesion promoter compositions curable in the presence of moisture.
U.S. Pat. No. 4,395,526 to White et al relates to a stable, substantially acid-free, one-component curable polyalkoxy-terminated organoolysiloxane composition having a condensation catalyst, such as a tin compound. The material in this patent also serves as an adhesion promoter.
Specific patents relating to acetoxy curing room temperature vulcanizable silicones include Ceyzeriat, U.S. Pat. Nos. 3,133,891, Brunner, 3,035,016, and Beers, 3,382,205. More specifically, the Beers' patent relates to organopolysiloxane compositions comprising a mixture of organotriacyloxysilane and a base mixture containing organosiloxane having chemically combined organsiloxy units.
U.S. Pat. No. 3,541,044 to Beers relates to a substantially anhydrous organopolysiloxane composition curable to the elastomeric state upon exposure to moisture. Another patent by Beers, namely U.S. Pat. No. 3,837,878 relates to a two-component room temperature vulcanizable silicone rubber composition suitable for molding applications whereas U.S. Pat. No. 3,837,878 also to Beers relates to a process for treating silicone fillers.
U.S. Pat. No. 3,776,933 to Toporcerer relates to chain extenders with regard to RTV systems.
While most of the above patents do relate to organopolysiloxane compositions, they do not teach one-component room temperature vulcanizable silicone sealant composition of the present invention or a di-substituted mixed oxime-alkoxysilylalkyl urea derivative as an adhesion promoter.